With reference to FIGS. 1-5, one prior art embodiment of a heat exchanger as described in Japanese Patent Application Publication No. 63-112065 is shown. As shown in the figures, a condenser 500 includes a plurality of adjacent, essentially flat tubes 11 having an oval cross-section and open ends which allow refrigerant fluid to flow therethrough. A plurality of corrugated fin units 12 are disposed between adjacent tubes 11. Flat tubes 11 and fin units 12 jointly form heat exchange region 100. Cylindrical header pipes 530 and 540 are disposed perpendicular to flat tubes 11 and may have, for example, a clad construction. The diameter and length of header pipes 530 and 540 are substantially equal to the thickness and height, respectively, of heat exchange region 100. Accordingly, header pipes 530 and 540 protrude only negligibly relative to heat exchange region 100 when the heat exchanger structure is assembled.
As shown in FIGS. 3 and 4, each of header pipes 530 and 540 includes an outer tube 13 which is preferably made of aluminum, and an inner tube 14, made of a metal material, which is brazed to the inner surface of outer tube 13. Outer tube 13 has a plurality of slots 15 disposed therethrough. Flat tubes 11 are fixedly connected to header pipes 530 and 540 and are disposed in slots 15 so that the open ends of flat tubes 11 communicate with the hollow interiors of header pipes 530 and 540. Inner tube 14 includes a plurality of portions 14a which define openings corresponding to slots 15. Portions 14a are brazed to the inner ends of flat tubes 11 and ensure that tubes 11 are hermetically sealed within header pipes 530 and 540 when the tubes are inserted in slots 15.
Referring again to FIGS. 1 and 2, header pipe 530 has an open top end and a closed bottom end. An L-shaped pipe member 533a is positioned in the open top end of pipe 530, and is fixedly and hermetically connected thereto at one of its ends. The other end of L-shaped pipe member 533a is sealed by an inlet union joint 533b which is fixedly and hermetically connected to pipe member 533a. Inlet union joint 533b is linked to an outlet of an element (not shown) positioned upstream with respect to condenser 500, for example, a compressor, through a pipe member (not shown). Inlet union joint 533b and L-shaped pipe member 533a jointly form inlet union joint assembly 533.
Header pipe 540 has a closed top end and an open bottom end. An L-shaped pipe member 543a is fixedly and hermetically connected at one of its ends to the open bottom end of header pipe 540. The other end of L-shaped pipe member 543a is sealed by an outlet union joint 543b which is fixedly and hermetically connected to pipe member 543a. Outlet union joint 543b is linked to an inlet of an element (not shown) positioned downstream with respect to condenser 500, for example, a receiver, through a pipe member (not shown). Outlet union joint 543b and L-shaped pipe member 543a jointly form outlet union joint assembly 543.
As can be seen from the figures, inlet and outlet union joint assemblies 533 and 543 excessively protrude from heat exchange region 100 and header pipes 530 and 540 when condenser 500 is assembled as shown in FIGS. 1 and 2.
Still referring to FIG. 1, a partition wall 20a is fixedly disposed within header pipe 530 at a location about midway along its length and divides header pipe 530 into an upper cavity 531 and a lower cavity 532, which is isolated from upper cavity 531. A partition wall 30a is fixedly disposed within header pipe 540 at a location approximately one-third of the way along the length of header pipe 540 and divides header pipe 540 into an upper cavity 541 and a lower cavity 542, which is isolated from upper cavity 541. The location of partition wall 30a is lower than the location of partition wall 20a.
In operation, compressed refrigerant gas from an external compressor coupled to inlet union joint assembly 533 flows into upper cavity 531 of header pipe 530 through the inlet union joint assembly, and is distributed so that a portion of the gas flows through each of flat tubes 11 which is disposed above the location of partition wall 20a, and into an upper portion of upper cavity 541. Thereafter, the refrigerant in the upper portion of cavity 541 flows downwardly into a lower portion of upper cavity 541, and is distributed so that a portion of the refrigerant flows through each of flat tubes 11 disposed below the location of partition wall 20a and above the location of partition wall 30a, and into an upper portion of lower cavity 532 of header pipe 530. The refrigerant in the upper portion of lower cavity 532 then flows downwardly into a lower portion of lower cavity 532, and is again distributed so that a portion of the refrigerant flows through each of flat tubes 11 disposed below the location of partition wall 30a, and into lower cavity 542 of header pipe 540. As the refrigerant gas sequentially flows through flat tubes 11, heat from the refrigerant gas is exchanged with the atmospheric air flowing through corrugated fin units 12 in the direction of arrow W as shown in FIG. 5. Because the refrigerant gas radiates heat to the outside air, it condenses to a liquid state as it travels through tubes 11. The condensed liquid refrigerant in cavity 542 flows out of the cavity through outlet union joint assembly 543 and into an external receiver coupled to the joint assembly.
With reference to FIGS. 6 and 7, another prior art heat exchanger is shown. In the figures, the same reference numerals are used to denote corresponding elements shown in FIGS. 1-5. A complete explanation of these elements is, therefore, omitted. As shown in the figures, condenser 600 includes first and second header pipes 630 and 640 which are closed at both ends. An opening 631 is provided in first header pipe 630 between its upper closed end and partition wall 20a. A straight pipe member 633a is disposed in opening 631 and is fixedly and hermetically connected to first header pipe 630 to communicate with the hollow interior of the header pipe. The other end of straight pipe member 633a is sealed by an inlet union joint 633b which is fixedly and hermetically connected to the pipe member. Inlet union joint 633b and straight pipe member 633a jointly form inlet union joint assembly 633.
An opening 641 is provided in second header pipe 640 between its lower closed end and partition wall 30a. An L-shaped pipe member 643a is disposed in opening 641 and is fixedly and hermetically connected to second header pipe 640 to communicate with the hollow interior of the header pipe. The other end of L-shaped pipe member 643a is sealed by an outlet union joint 643b which is fixedly and hermetically connected to the pipe member. Outlet union joint 643b and L-shaped pipe member 643a jointly form outlet union joint assembly 643.
As can be seen from the figures, in this prior art arrangement, inlet and outlet union joint assemblies 633, 643 excessively protrude from the heat exchange region and header pipes 630 and 640 when condenser 600 is assembled as shown in FIGS. 6 and 7.
As described above, in the prior art structures, the inlet and outlet union joint assemblies excessively protrude from the heat exchange region and the header pipes when the condenser is assembled. Thus, when the condenser is installed in the engine compartment of an automobile, the inlet and outlet union joint assemblies may interfere with other components disposed within the engine compartment. Further, if the size of the condenser is reduced in order to prevent this interference, the heat exchange ability of the condenser is decreased as a result of the reduction in size of the heat exchange area.